Trump orders creation of 'space force'

US President Donald Trump is ordering the establishment of a sixth branch of the military to clear the way for American dominance of space.

"It is not enough to merely have an American presence in space. We must have American dominance in space," Trump said on Monday before a meeting of his National Space Council.

"We are going to have the Air Force and we're going to have the 'Space Force'. Separate but equal. It is going to be something. So important," he said later.

The US, however, is a member of the Outer Space Treaty, which bars the stationing of weapons of mass destruction in space and only allows for the use of the moon and other celestial bodies for peaceful purposes.

Trump also signed a directive on the management of traffic and debris in space.

The announcements were his administration's latest moves to scale up US space exploration. The US wants to send robotic explorers to the moon as soon as next year as a preparatory step towards sending astronauts back there for the first time since 1972, a NASA official said on Monday.

The National Aeronautics and Space Administration is planning a series of lunar missions beginning next year aimed at developing the capacity for a return to the moon, said Cheryl Warner, a spokeswoman for NASA's Human Exploration Directorate.

NASA will work with private companies, which have not yet been chosen, on the missions, Warner said in a phone interview.

In December, Trump signed a directive that he said would enable astronauts to return to the moon and eventually lead a mission to Mars. He ordered the government last month to review regulations on commercial space flights.

President Donald Trump. (AAP) (AAP)

Americans first landed on the moon in 1969, reaching a goal set by former president John F. Kennedy in 1961 and capping a decade-long space race between Washington and Moscow.

Since then, US efforts to explore beyond the Earth's orbit have largely focused on remote spacecraft that do not have human crew members, though American presidents have repeatedly raised the idea of sending human explorers back to the moon or further.

President George W. Bush in 2004 said humans would return to the moon by 2020. His successor, President Barack Obama, said in 2016 the US would send humans to Mars by the 2030s.